Representatives Russ Carnahan and Jerry Costello broke with House Democrats on Tuesday and kept their names off a brief urging a federal appeals court to strike down the Defense of Marriage Act, which prohibits the federal government from recognizing same-sex marriages. Carnahan says he's committed to supporting civil rights and is simply focusing on legislation at this time.

Carnahan's opponent in an increasingly bitter August 7 primary race, Wm. Lacy Clay signed the brief, which is in support of Karen Golinski, a California woman and federal court employee who is suing the federal government for denying equal health insurance benefits for her wife.

Costello, whose district covers southern Illinois and parts of the St. Louis suburbs, has consistently voted in favor of legislation that outlaws same-sex marriage. After 24 years in Congress, he is not seeking re-election and Illinois Democrats have been scrambling to hold onto the seat in the largely conservative district.

AJ Bockelman, executive director of PROMO, Missouri's LGBT advocacy group, said Clay and Carnahan are on equal footing when it comes to supporting the gay community.

"My experience has been that all three of our Democratic House Caucus have tended to be strong supporters (that includes [Rep. Emmanual] Cleaver out of KC)," Bockelman said via email. "There are a number of bills and other actions that come out from Congress Members that all depend on what constituents have put in front of them."

Brief or no brief, Carnahan says he supports ending DOMA. He agreed to co-sponsor the Respect for Marriage Act, a bill pending in Congress that calls for the repeal of DOMA, on June 8, roughly two months after Clay had signed on and a year and a half after the bill was first introduced.

"I remain committed to equality of human rights, both here and abroad," Carnahan said via a spokesperson. "I believe it is most important for my constituents for me to show my support by doing my job, writing and supporting actual legislation that can change the path our nation is on, and improve the lives of Americans who face discrimination every day. I will continue standing up here in Congress and doing exactly that."